1. Field of the Invention
The present invention relates to improvements in electronic stethoscopes of the type which include sound amplification and more particularly to a novel housing and component placement for reduction of electronic and acoustical or environmental noise. A visual signal is also produced by the amplifier circuitry which is proportional to the power surges in the amplifier circuit thus providing an efficient and reliable blood flow indication when desired. Although the Stethoscope of the present invention is adaptable for widespread use in the medical field, it has particular advantages when used in medical emergency or medical aid units by doctors or paramedicals who need to immediately determine heartbeat, blood flow or respiratory sounds in an environment with high noise levels. Heartbeat, blood flow and other functions may be detected with a fully clothed patient or accident victim.
2. The Prior Art
In the prior art electronic stethoscopes have been provided with housing structures and component placement such that a high degree of noise interference is experienced. These devices are subjected to interference from the electronic circuitry and from any shock impact or other disturbance to the speaker or microphone housing and by the general environmental noise level. Examples of prior electronic stethoscopes are found in the U.S. Pat. Nos. 2,755,336 to F.B. Zinner et al.; 3,247,324 to R. Cefaly et al.; and 4,254,302 to Walsh. In most of these devices, the problem is compounded by the fact that a sensitive electronic microphone is placed directly in the acoustic transducer portion of the conventional stethoscope structure or is used in lieu thereof. Additionally, insufficient acoustic and electronic insulation is utilized in the electronic component housing and placement of the components is such as to increase rather that limit noise interference. Additionally, adequate provision has not been made to detect such functions as blood flow with visual indication combined with the normal stethoscope function.